1. Field of the Invention
The present invention relates to an ink jet printer, and, more particularly, to a method of printing with high resolution using an ink jet printer.
2. Description of the Related Art
An ink jet printhead includes a plurality of nozzles arranged vertically, i.e., in the paper feed direction, with respect to a printed page. The nozzles have a fixed vertical spacing between them, such as {fraction (1/600)} inch for a 600 dots per inch (dpi) printhead. Additionally, the array of nozzles travels horizontally repeatedly across the page, with some amount of advance of the paper in the vertical direction between such scans, dropping dots at a fixed horizontal distance, which can also be {fraction (1/600)} inch. The term xe2x80x9chorizontalxe2x80x9d, as used herein, indicates the direction of printhead scan, perpendicular to the vertical, paper feed direction. According to the present example, the vertical pitch of the nozzles, in combination with the horizontal distance between dots as they are placed on the page, define a printing grid, or matrix, of a given vertical and horizontal resolution.
Typically, the combined behavior of the horizontal scanning of the nozzle array and the amount of vertical paper feed between consecutive scans allows exactly one drop of ink to be placed at every pixel position of the printing grid. In this condition, the grid is said to be xe2x80x9cperfectly covered.xe2x80x9d Each pixel position has one opportunity to be printed on exactly one scan of the printhead and by exactly one nozzle of the printhead.
The well known technique of xe2x80x9cshinglingxe2x80x9d employs a method whereby the printing grid is xe2x80x9csuper coveredxe2x80x9d, meaning that the horizontal scanning behavior and the vertical paper feed allow that each pixel position has multiple opportunities in which a drop of ink can be placed at that position. Typically, these multiple opportunities are available in different scans of the head, which implies that the multiple opportunities are realized by different nozzles of the printhead.
A problem is that multiple passes of the printhead over the same raster line decreases the print speed of the printer. Another problem is that the amount of information that can be transferred to the print medium is limited by the fact that only one size of ink drop can be deposited on the print medium. Thus, only through the selection of locations at which the single-sized ink drops are deposited can the information be conveyed to the print medium.
What is needed in the art is a method of transferring more information to the print medium without requiring more passes of the printhead.
The present invention provides a method of printing at a higher resolution with fewer passes of a multiple-sized-nozzle printhead.
The invention, in one form thereof, relates to a method of printing with an ink jet printer. A printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size is provided. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Print data corresponding to first columns of pixel locations is provided. The print data includes for each pixel location in the first columns both a respective large dot print datum and a respective small dot print datum. One of the respective large dot print datum and the respective small dot print datum is printed at a first pixel location of the corresponding pixel locations in the first columns. Second columns of pixel locations interleaved with the first columns of pixel locations are provided. The other of the respective large dot print datum and the respective small dot print datum not printed in the first pixel location of the first columns is printed at a first pixel location of the second columns of pixel locations.
In another form thereof, the method includes the steps of providing a printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size; providing print data corresponding to first columns of pixel locations, the print data including both a respective large dot print datum and a respective small dot print datum corresponding to each pixel location in the first columns of pixel locations; printing one of the respective large dot print datum and the respective small dot print datum onto the each pixel location in the first columns; providing second columns of pixel locations interleaved with the first columns of pixel locations, each pixel location in the second columns corresponding to a respective pixel location in the first columns; and printing an other of the respective large dot print datum and the respective small dot print datum not printed in the first columns onto each the corresponding pixel locations in the second columns.
The invention, in another form thereof, relates to a method of printing with an ink jet printer. A printhead has a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. A first set of pixel locations is defined that receives ink only from the first nozzles. A second set of pixel locations is defined that receives ink only from the second nozzles. The pixel locations from the first set and the pixel locations from the second set are alternatingly disposed in a horizontal direction. The first nozzles jet ink onto the first set of pixel locations. The second nozzles jet ink onto the second set of pixel locations.
The invention, in yet another form thereof, relates to a method of printing with an ink jet printer. A printhead has a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Each first nozzle is separated from an adjacent second nozzle by a first distance. A matrix of pixel locations is defined that includes a plurality of first pixel locations and a plurality of second pixel locations. The first pixel locations receive ink only from the first nozzles. The second pixel locations receiving ink only from the second nozzles. The matrix includes adjacent rows separated from each other by a second distance equal to one-half of the first distance. Pairs of the first pixel locations and pairs of the second pixel locations are alternatingly aligned in each vertical column of the matrix. The printhead jets ink onto the matrix of pixel locations.
The invention, in a further form thereof, relates to a method of printing with an ink jet printer. A printhead has a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Each first nozzle is separated from an adjacent second nozzle by a first distance in the vertical direction. A matrix of pixel locations is defined that includes a plurality of first pixel locations, a plurality of second pixel locations, and a plurality of third pixel locations. The first pixel locations receiving ink only from the first nozzles. The second pixel locations receiving ink only from the second nozzles. The third pixel locations receive ink from the first nozzles and the second nozzles. The matrix includes adjacent rows separated from each other by a second distance equal to one-half of the first distance. Each first pixel location is separated from at least one second pixel location by the first distance in the vertical direction. Each second pixel location is separated from at least one first pixel location by the first distance in the vertical direction. Each third pixel location is separated from at least one other third pixel location by the first distance in the vertical direction. The printhead jets ink onto the matrix of pixel locations.
An advantage of the present invention is that the large nozzles can fill in dark colors with fewer passes of the printhead, and the small nozzles can be used where less grain is needed.
Another advantage of the present invention is that more information is transferred to the print medium without requiring additional passes of the printhead.